An Introduction to the Appendicular Skeleton
An Introduction to the Appendicular Skeleton
The Appendicular Skeleton
126 bones
Allows us to move and manipulate objects
Includes all bones besides axial skeleton
The limbs
The supportive girdles
The Pectoral Girdle
Also called the shoulder girdle
Connects the arms to the body
Positions the shoulders
Provides a base for arm movement
Consists of
Two clavicles
Two scapulae
Connects with the axial skeleton only at the manubrium
Also called collarbones
Long, S-shaped bones
Originate at the manubrium (sternal end)
Articulate with the scapulae (acromial end)
The Scapulae
Also called shoulder blades
Broad, flat triangles
Articulate with arm and collarbone
Anterior surface: the subscapular fossa
Structures of the scapula
Body has three sides:
superior border
medial border (vertebral border)
lateral border (axillary border)
Body has three corners:
superior angle
inferior angle
lateral angle
The scapular head
Holds glenoid cavity
Which articulates with humerus
To form shoulder joint
Processes of the glenoid cavity
Coracoid process:
anterior, smaller
Acromion:
posterior, larger
articulates with clavicle
at the acromioclavicular joint
Posterior features of the scapula
Scapular spine:
ridge across posterior surface of body
Separates two regions:
supraspinous fossa
infraspinous fossa
The Upper Limbs
The upper limbs consist of the arms, forearms, wrists, and hands
Note: arm (brachium) = 1 bone, the humerus
The Humerus
Also called the arm
The long, upper arm bone
Articulates with the pelvic girdle
Tubercles of the proximal epiphysis
Separated by the intertubercular groove:
greater tubercle:
lateral
forms tip of shoulder
lesser tubercle:
anterior, medial
Head:
Rounded, articulating surface
Contained within joint capsule
Anatomical neck:
Margin of joint capsule
Surgical neck:
The narrow metaphysis
The Shaft
Deltoid tuberosity:
a bulge in the shaft
attaches deltoid muscle
Radial groove:
for radial nerve
posterior to deltoid tuberosity
The distal epiphysis
Medial and lateral epicondyles:
for muscle attachment
Condyle of the humerus:
articulates with ulna and radius
Articular regions of the condyle
Trochlea:
coronoid fossa and olecranon fossa
articulates with ulna
Capitulum:
radial fossa
articulates with radius
The Forearm (also called the antebrachium)
Consists of two long bones
Ulna (medial)
Radius (lateral)
The Ulna
The olecranon
Superior end of ulna
Point of elbow
Superior lip of trochlear notch
Articulates with trochlea of humerus
The coronoid process
Inferior lip of trochlear notch
The Ulna
Articulations with the humerus
Forearm extended:
olecranon enters olecranon fossa
Forearm flexed:
coronoid process enters coronoid fossa
Other articulations
Radial notch:
articulates with head of radius
forms proximal radio-ulnar joint
Ulnar head:
prominent styloid process
attaches to articular disc between forearm and wrist
The Ulna
Interosseous membrane
A fibrous sheet
Connects lateral margin of ulnar shaft to radius
The Radius
Lateral bone of forearm
Disk-shaped radial head above the neck
Radial tuberosity below the neck, attaches biceps
Articulations of the radius
Ulnar notch:
distal end
articulates with wrist and radius
Styloid process:
stabilizes wrist joint
Eight carpal bones
Four proximal carpal bones
Four distal carpal bones
Allow wrist to bend and twist
The Four Proximal Carpal Bones
Scaphoid
Near styloid process
Lunate
Medial to scaphoid
Triquetrum
Medial to lunate bone
Pisiform
Anterior to triquetrum
The Four Distal Carpal Bones
Trapezium
Lateral
Trapezoid
Medial to trapezium
Capitate
Largest
Hamate
Medial, distal
Metacarpal Bones
The five long bones of the hand
Numbered I–V from lateral (thumb) to medial
Articulate with proximal phalanges
Phalanges of the Hands (14 total finger bones)
Pollex (thumb)
Two phalanges (proximal, distal)
Fingers
Three phalanges (proximal, middle, distal)
The Pelvic Girdle
Made up of two hip bones (coxal bones)
Strong to bear body weight, stress of movement
Part of the pelvis
Coxal bones
Made up of three fused bones
Ilium (articulates with sacrum)
Ischium
Pubis
The Pelvic Girdle
Coxal Bones
The acetabulum
Also called the hip socket
Is the meeting point of the ilium, ischium, and pubis
Is on the lateral surface of the hip bone (coxal bone)
Articulates with head of the femur (lunate surface)
Acetabular notch
A gap in the ridge of the margins of the acetabulum
Marks of the Ilium
Greater sciatic notch
For sciatic nerve
Iliac crest
Upper brim
Iliac fossa
Depression between iliac crest and arcuate line
The Pelvic Girdle
Marks of the Ischium
Ischial spine
Above lesser sciatic notch
Ischial tuberosity
Posterior projection you sit on
Ischial ramus
Meets inferior ramus of pubis
Superior ramus
Meets pubic tubercle
Marks of the Pubis
Pubic symphysis
Gap between pubic tubercles
Padded with fibrous cartilage
Obturator foramen
Formed by ischial and pubic rami
Attaches hip muscles
Pectineal line
Ridge of superior ramus of pubis
Continues to iliac crest as arcuate line (both of the ilium)
Coxal Bones
Articulations of the pelvic girdle
Sacroiliac joint
Articulation of posterior auricular surface of ilium
With the sacrum
Stabilized by ligaments of iliac tuberosity
The Pelvis
Consists of two coxal bones, the sacrum, and the coccyx
Stabilized by ligaments of pelvic girdle, sacrum, and lumbar vertebrae
Divisions of the Pelvis
True pelvis
Encloses pelvic cavity
Pelvic brim:
upper edge of true pelvis
encloses pelvic inlet
Perineum region:
inferior edges of true pelvis
forms pelvic outlet
perineal muscles support organs of pelvic cavity
False pelvis:
Blades of ilium above arcuate line
Comparing the Male Pelvis and Female Pelvis
Female pelvis
Smoother and lighter
Less prominent muscle and ligament attachments
Pelvis modifications for Childbearing
enlarged pelvic outlet
broad pubic angle (>100°)
less curvature of sacrum and coccyx
wide, circular pelvic inlet
broad, low pelvis
ilia project laterally, not upwards
The Lower Limbs
Functions of the lower limbs
Weight bearing
Motion
Note: leg = lower leg; thigh = upper leg
Bones of the Lower Limbs
Femur (thigh)
Patella (kneecap)
Tibia and fibula (leg)
Tarsals (ankle)
Metatarsals (foot)
Phalanges (toes)
The Femur
The proximal epiphysis
Femoral head:
articulates with pelvis at acetabulum
attaches at fovea capitis
The neck:
Narrow area between head and trochanters
Joins shaft at angle
The proximal epiphysis
Trochanters:
greater trochanter and lesser trochanter:
tendon attachments
intertrochanteric line (anterior) and intertrochanteric crest (posterior):
mark edge of articular capsule
The shaft
Linea aspera:
most prominent ridge of shaft
attaches hip muscles
joins epicondyles
The distal epiphysis
Medial epicondyle and lateral epicondyle:
above the knee joint
Medial condyle and lateral condyle:
separated by intercondylar fossa and patellar surface
form part of knee joint
The Patella
Also called the kneecap
A sesamoid bone
Formed within tendon of quadriceps femoris
Base attaches quadriceps femoris
Apex attaches patellar ligament
The Tibia
Also called the shinbone
Supports body weight
Larger than fibula
Medial to fibula
The proximal epiphysis
Medial and lateral tibial condyles:
separated by intercondylar eminence
articulate with medial and lateral condyles of femur
Tibial tuberosity:
attaches patellar ligament
The shaft
Anterior margin:
sharp ridge of shinbone
The distal epiphysis
Medial malleolus:
medial projection at the ankle
The Fibula
Attaches muscles of feet and toes
Smaller than tibia
Lateral to tibia
Articulations with tibia
Fibula/tibia articulations:
head
inferior tibiofibular joint
Interosseous membrane:
binds fibula to tibia
Lateral malleolus:
lateral projection of ankle
The Ankle
Also called the tarsus
Consists of seven tarsal bones
Bones of the ankle
Talus:
carries weight from tibia across trochlea
Calcaneus (heel bone):
transfers weight from talus to ground
attaches calcaneal (Achilles) tendon
Cuboid:
articulates with calcaneus
Bones of the ankle
Navicular:
articulates with talus and three cuneiform bones
Medial cuneiform
Intermediate cuneiform
Lateral cuneiform
Metatarsal Bones of the Foot
Five long bones of foot
Numbered I–V, medial to lateral
Articulate with toes
Phalanges of the foot
Phalanges
14 bones of the toes
Hallux
Big toe or great toe, two phalanges (distal, proximal)
Other four toes
Three phalanges (distal, medial, proximal)
Arches of the Feet
Arches transfer weight from one part of the foot to another
The longitudinal arch
Calcaneal portion:
lateral
Talar portion:
medial
The transverse arch
Formed by a difference in curvature between medial and lateral borders of the foot
Individual Skeleton Variation
Studying the Skeleton
Reveals characteristics
Muscle strength and mass (bone ridges, bone mass)
Medical history (condition of teeth, healed fractures)
Sex and age (bone measurements and fusion)
Body size
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